Vol. 84, No. 49, pp. 427-434 29 February 1972 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON A NEW GENUS AND NEW SPECIES OF WATER BEETLE FROM BOLIVIA WITH A KEY TO THE GENERA OF THE WESTERN HEMISPHERE COLYMBETINI ( COLEOPTERA: DYTISCIDAE )1 BY PAUL J. SPANGLER Smithsonian Institution, Washington, D. C. 20560 The interesting new genus and species of dytiscid beetle described below was collected in 1969 during an extended field trip in South America. The new genus keys to the tribe Colymbetini and to the genus Meladema in Zimmerman's ( 1919 ) review of the subfamily Colymbetinae. In Brinck's ( 1948 ) review of the tribes of the subfamily Colymbetinae, this new genus does not key clearly to the Colymbetini because the metatarsal segments are not distinctly lobed on the outer, lower part but are feebly lobed only on the basal two segments. However, in comparing the other genera in the Colymbetinae with the new Bolivian form, I found that some other species in the tribe Colymbetini, e.g., Rhantus vianus Aube and R. validus Sharp, possess feebly lobed metatarsal segments similar to the new genus. Because this new genus keys satisfactorily in Zimmerman's key and agrees with Brinck's analysis of the Colymbetini in all char- acters except the variable lobing of the hind tarsal segments, I assign this new genus to the Colymbetini. Bunites new genus Head large, broadest across eyes. Eyes emarginate above bases of antennae. Labrum broadly emarginate medially, with dense fringe of golden setae in emargination. Clypeus arcuate anteriorly. Maxillary palpus 4 segmented; basal segment short, about one-third length of 1 This study was made possible by Smithsonian Institution Grant No. 5a063310. 49—PRoc. Bloc. Soc. WASH., VOL. 84, 1971 (427) 428 Proceedings of the Biological Society of Washington second segment; second segment slightly shorter than third segment; third segment slightly shorter than fourth segment; fourth segment swollen, with a glabrous dorsal sensory region at basal third, a glabrous and depigmented lateral sensory region at apical fourth and a ventral seta-bearing area at apical third. Ligula subquadrate. Anterior margin of mentum bisinuate. Labial palpus 3 segmented; basal segment short, about one-third as long as second segment; second and third segments subequal; third segment swollen just beyond rnidlength ( in lateral view), with 2 fine seta-bearing sensory areas ventrally at apical third. Pronotum more than twice as wide as long; margined laterally; antero- lateral angles acute, prolonged anteriorly; posterolateral angles obtuse; base narrower than base of elytra. Prosternum convex medially. Pro- sternal process distinctly convex; margined; apex acute, extending be- tween mesocoxae and fitting in a deep notch in metasternum. Elytra convex; slightly wider at apical third; base wider than base of pronotum; narrowly margined laterally. Metasternal wings broadly wedge-shaped. Metasternum with a weak longitudinal sulcus becoming deeper between metacoxal processes. Metacoxal plates broad, slightly incised along posterior margin. Metacoxal lines well separated and diverging anteriorly. Pleurite of second abdominal segment ( first visible segment) with strong, transverse rugae. Male with basal protarsal segment ( Fig. 2) longer than next 3 seg- ments combined ( in lateral view). Basal mesotarsal segment shortei than segments 2, 3, and 4 combined. Pro- and mesotarsal claws long, stout, and equal in length. Metatibia with several discontinuous, medial, longitudinal rows of large aciculate seta-bearing punctures on anterior ( ventral) surface. Basal metatarsal segment longest, twice as long as second segment; metatarsal segments, at most, very slightly lobed in outer lower part; outer metatarsal claw curved and shorter than straighter inner claw. Profemur stout; anterior surface swollen medially and covered with coarse, seta-bearing punctures; with a densely setose sul- cus along lower, outer half near hind margin. Mesofemur similar to profemur but lacks the densely setose sulcus. Metafemur gradually widening from base to apex; anterolateral angle strongly rounded; postero- lateral angle feebly rounded, almost forming a right-angle. Parameres ( Figs. 3, 6) of male genitalia broadest and curved near base, tapering to slender apices; underside densely pubescent in apical three-fourths. Median lobe curved ( side view ) and tip recurved ( Fig. 5); slightly sinuous and cleft (Fig. 4) from midlength to apex in dorsal view. Type of the genus: Bunites phyllisae new species. Etymology: Bunites from bounites, G.—dweller in the hills. Gender: masculine. The new genus Bunites may be distinguished from the Old World genus Meladema by the presence of slightly unequal metatarsal claws A New Dytiscid from Bolivia 429 and several discontinuous, medial, longitudinal rows of large aciculate seta-bearing punctures on anterior ( ventral) surface of the metatibia. Meladema has distinctly unequal metatarsal claws and the metatibia has a medial, continuous, longitudinal stria on the anterior ( ventral) sur- face. The new genus may be separated from the genera of the Colymbetini occurring in the Western Hemisphere by the following key. KEY TO THE GENERA OF THE TRIBE COLYMBETINI OF THE WESTERN HEMISPHERE 1. Prosternal process flat; dorsal surface of beetle unusually flat; pronotum widely margined laterally; elytra lightly reticulate throughout, meshes rather coarse, unequal, and irregular in shape; North America Hoperius Fall Prosternal process convex or carinate, not flat; pronotum margined or not; elytra coarsely or finely reticulate or with transverse grooves 2 2. Elytral sculpture consisting of many parallel transverse grooves; apex of metasternum strongly depressed and indistinctly notched for apex of prosternal process; North America Colymbetes Clairville Elytra without transverse grooves, reticulate; apex of metasternum slightly or not depressed but distinctly notched for apex of poststernal process 3 3. Body form ovate; sides evenly arcuate, uninterrupted; sides of pronotum continuous with elytra; base of pronotum same width as base of elytra; pronotum usually margined; color usually not black; North, Central, and South America Rhantus Dejean Body form oblong; sides not evenly arcuate, interrupted; sides of pronotum not forming a continuous arc with elytra; base of pronotum narrower than base of elytra; pronotum margined or not; color black 4 4. Pronotum without lateral margin, posterolateral angles acute; ely- tral reticulation coarse; apex of prosternal spine fits into a shallow notch on apex of metasternum; front tibia incised on inner side at base, strongly so in male; metatarsal segments distinctly lobed on outer, lower part; North America Neoscutopterus J. Balfour-Browne Pronotum with lateral margin, posterolateral angles obtuse; ely- tral reticulation fine; apex of prosternal spine fits into a deep notch on apex of metasternum; front tibia not incised on inner side at base; only basal 2 metatarsal segments moderately lobed on outer, lower part; South America Bunites Spangler 430 Proceedings of the Biological Society of Washington Fics. 1-7. Bunites phyllisae new genus, new species, 8 holotype: 1. habitus, dorsal view; 2. left protarsus, ventral view; 3. right para- mere, medial view; 4. apex, median lobe, dorsal view; 5. median lobe, lateral view; 6. left paramere, medial view; 7. right metatarsus, ventral view. A New Dytiscid from Bolivia 431 Bunites phyllisae new species Figures 1-7 Holotype male: Length 14.00 mm, greatest width 6.50 mm at apical third. Color of head, pronotum, and elytra piceous except transverse, reddish-yellow macula on middle of head between eyes and short longi- tudinal, reddish-yellow macula near lateral margin slightly behind mid- length on elytron. Epipleuron dark reddish brown. Ventral side of body piceous except metacoxae, posterolateral margins of third, fourth, and fifth abdominal sterna, middle two-fourths of sixth sternum, and last 3 or 4 antennal segments dark reddish brown. Head finely alutaceous; with numerous, fine punctures scattered over surface, punctures separated by a distance of 1 to 4 times their diam- eter; with a deep, short, setose, transverse sulcus at anterolateral angle adjacent to labrum; with a few coarse punctures along margin of clypeus between sulci; also a row of coalesced punctures along inner margin of eye, another shorter group of punctures along frontoclypeal suture and a few coalesced punctures between eye and frontoclypeal suture. Clyp- eus arcuate anteriorly. Labrum finely alutaceous and finely, sparsely punctate; broadly emarginate medially, with dense fringe of golden setae in emargination. Ventral surface of head microreticulate laterally behind eyes; ligula subquadrate and smooth except for a few fine punc- tures on surface; mentum bisinuate along anterior margin, surface weakly rugose medially, finely alutaceous laterally, with few coarse shallow punctures. Antenna 11 segmented, basal segment longest, second seg- ment shortest, remainder subequal. Maxillary palpus 4 segmented; basal segment short, about one-third length of second segment; second seg- ment slightly shorter than third segment; third segment slightly shorter than fourth segment; fourth segment swollen, with a glabrous dorsal sen- sory region at basal third, a glabrous and depigmented lateral sensory region at apical fourth and a ventral seta-bearing area at apical third. Labial palpus 3 segmented; first segment short, about one-third as long as second segment; second and third segments subequal; third